alt Hacker News> We don't have any flags left for that that.
There's the reserved bit (aka the evil bit[1]). Are you saying gear out there drops packets with reserved bit set to 1? Wouldn't surprise me, just curious.
Seems like IPv4+ would have been a good time to use that bit. Any IPv4+ packets could have more flags in the + portion of the header, if needed.
That bit is currently defined as "Bit 0: reserved, must be zero", so there will be network gear out there, that either drops the packet otherwise or resets the bit to 0 when forwarding.